Theodore Winthrop Arms was born around November 1844 in Norwich, Connecticut, to Hiram Phelps Arms and Abby Jane Baker. His father was a minister who owned $2,500 of real estate by 1850. Arms grew up and attended school in Norwich. He married Rosa Marselis in Woodbury, New Jersey, on October 13, 1869, and they had at least three children: Helen, born around 1871; Lucy, born around 1872; and Theodore, born around 1873.
They lived in Upper Augusta, Pennsylvania, and Arms worked as a clerk in a railroad office. By 1870, they owned $2,700 of real estate and $600 of personal property. They moved to Medford, Massachusetts, in the 1870s, and Arms served as a Paymaster’s Clerk in the United States Navy. They employed at least two white domestic servants. His wife died on November 11, 1890, and he married Marielle Loughead on March 1, 1892. They lived in Arlington, Massachusetts.
Arms retired from the navy in 1910, and they settled in Brooklyn, New York. Marielle died on November 8, 1914. By 1920, he was living with his daughter Lucy and a maid in Brooklyn. He spent his winters in Orlando, Florida, and he died there of a cerebral hemorrhage on April 9, 1928.